freeswitch/src/switch_xml.c

/* 
 * FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 * Copyright (C) 2005/2006, Anthony Minessale II <anthmct@yahoo.com>
 *
 * Version: MPL 1.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is FreeSWITCH Modular Media Switching Software Library / Soft-Switch Application
 *
 * The Initial Developer of the Original Code is
 * Anthony Minessale II <anthmct@yahoo.com>
 * Portions created by the Initial Developer are Copyright (C)
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 * 
 * Anthony Minessale II <anthmct@yahoo.com>
 *
 *
 * switch_xml.c -- XML PARSER
 *
 * Derived from EZXML http://ezxml.sourceforge.net
 * Original Copyright
 *
 * Copyright 2004, 2005 Aaron Voisine <aaron@voisine.org>
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <switch.h>
#include <ctype.h>
#include <sys/stat.h>
#ifdef HAVE_MMAP
#include <sys/mman.h>
#endif

#define SWITCH_XML_WS   "\t\r\n "  // whitespace
#define SWITCH_XML_ERRL 128        // maximum error string length

typedef struct switch_xml_root *switch_xml_root_t;
struct switch_xml_root {       // additional data for the root tag
    struct switch_xml xml;     // is a super-struct built on top of switch_xml struct
    switch_xml_t cur;          // current xml tree insertion point
    char *m;              // original xml string
    switch_size_t len;    // length of allocated memory for mmap
	uint8_t dynamic;
    char *u;              // UTF-8 conversion of string if original was UTF-16
    char *s;              // start of work area
    char *e;              // end of work area
    char **ent;           // general entities (ampersand sequences)
    char ***attr;         // default attributes
    char ***pi;           // processing instructions
    short standalone;     // non-zero if <?xml standalone="yes"?>
    char err[SWITCH_XML_ERRL]; // error string
};

char *SWITCH_XML_NIL[] = { NULL }; // empty, null terminated array of strings

struct switch_xml_binding {
	switch_xml_search_function_t function;
	switch_xml_section_t sections;
	struct switch_xml_binding *next;
};

typedef struct switch_xml_binding switch_xml_binding_t;
static switch_xml_binding_t *BINDINGS = NULL;
static switch_xml_t MAIN_XML_ROOT = NULL;
static switch_memory_pool_t *XML_MEMORY_POOL;
static switch_mutex_t *XML_LOCK;
static switch_thread_rwlock_t *RWLOCK;
static uint32_t lock_count = 0;

struct xml_section_t {
	const char *name;
	switch_xml_section_t section;
};


static struct xml_section_t SECTIONS[] = {
	{ "result", SWITCH_XML_SECTION_RESULT},
	{ "config", SWITCH_XML_SECTION_CONFIG},
	{ "directory", SWITCH_XML_SECTION_DIRECTORY},
	{ "dialplan", SWITCH_XML_SECTION_DIALPLAN},
	{ NULL, 0}
};

SWITCH_DECLARE(switch_xml_section_t) switch_xml_parse_section_string(char *str)
{
	size_t x;
	char buf[1024] = "";
	switch_xml_section_t sections = SWITCH_XML_SECTION_RESULT;

	if (str) {
		for(x = 0; x < strlen(str); x++) {
			buf[x] = (char)tolower((int)str[x]);
		}
		for(x = 0;;x++) {
			if (!SECTIONS[x].name) {
				break;
			}
			if (strstr(buf, SECTIONS[x].name)) {
				sections |= SECTIONS[x].section;
			}
		}
	}
	return sections;
}

SWITCH_DECLARE(switch_status_t) switch_xml_bind_search_function(switch_xml_search_function_t function, switch_xml_section_t sections)
{
	switch_xml_binding_t *binding = NULL, *ptr = NULL;
	assert(function != NULL);

	if (!(binding = switch_core_alloc(XML_MEMORY_POOL, sizeof(*binding)))) {
		return SWITCH_STATUS_MEMERR;
	}

	binding->function = function;
	binding->sections = sections;

	switch_mutex_lock(XML_LOCK);
	for (ptr = BINDINGS; ptr && ptr->next; ptr = ptr->next);

	if (ptr) {
		ptr->next = binding;
	} else {
		BINDINGS = binding;
	}
	switch_mutex_unlock(XML_LOCK);
	
	return SWITCH_STATUS_SUCCESS;
}


SWITCH_DECLARE(switch_xml_t) switch_xml_find_child(switch_xml_t node, char *childname, char *attrname, char *value)
{
	switch_xml_t p = NULL;

	if (!(childname && attrname && value)) {
		return node;
	}

	for (p = switch_xml_child(node, childname); p; p = p->next) {
		const char *aname = switch_xml_attr(p, attrname);
		if (aname && value && !strcasecmp(aname, value)) {
			break;
		}
	}

	return p;
}

// returns the first child tag with the given name or NULL if not found
SWITCH_DECLARE(switch_xml_t) switch_xml_child(switch_xml_t xml, const char *name)
{
    xml = (xml) ? xml->child : NULL;
    while (xml && strcmp(name, xml->name)) xml = xml->sibling;
    return xml;
}

// returns the Nth tag with the same name in the same subsection or NULL if not
// found
switch_xml_t switch_xml_idx(switch_xml_t xml, int idx)
{
    for (; xml && idx; idx--) xml = xml->next;
    return xml;
}

// returns the value of the requested tag attribute or "" if not found
SWITCH_DECLARE(const char *) switch_xml_attr_soft(switch_xml_t xml, const char *attr)
{
	const char *ret = switch_xml_attr(xml, attr);

	return ret ? ret : "";
}

// returns the value of the requested tag attribute or NULL if not found
SWITCH_DECLARE(const char *) switch_xml_attr(switch_xml_t xml, const char *attr)
{
    int i = 0, j = 1;
    switch_xml_root_t root = (switch_xml_root_t)xml;

    if (! xml || ! xml->attr) return NULL;
    while (xml->attr[i] && strcmp(attr, xml->attr[i])) i += 2;
    if (xml->attr[i]) return xml->attr[i + 1]; // found attribute

    while (root->xml.parent) root = (switch_xml_root_t)root->xml.parent; // root tag
    for (i = 0; root->attr[i] && strcmp(xml->name, root->attr[i][0]); i++);
    if (! root->attr[i]) return NULL; // no matching default attributes
    while (root->attr[i][j] && strcmp(attr, root->attr[i][j])) j += 3;
    return (root->attr[i][j]) ? root->attr[i][j + 1] : NULL; // found default
}

// same as switch_xml_get but takes an already initialized va_list
static switch_xml_t switch_xml_vget(switch_xml_t xml, va_list ap)
{
    char *name = va_arg(ap, char *);
    int idx = -1;

    if (name && *name) {
        idx = va_arg(ap, int);    
        xml = switch_xml_child(xml, name);
    }
    return (idx < 0) ? xml : switch_xml_vget(switch_xml_idx(xml, idx), ap);
}

// Traverses the xml tree to retrieve a specific subtag. Takes a variable
// length list of tag names and indexes. The argument list must be terminated
// by either an index of -1 or an empty string tag name. Example: 
// title = switch_xml_get(library, "shelf", 0, "book", 2, "title", -1);
// This retrieves the title of the 3rd book on the 1st shelf of library.
// Returns NULL if not found.
SWITCH_DECLARE(switch_xml_t) switch_xml_get(switch_xml_t xml, ...)
{
    va_list ap;
    switch_xml_t r;

    va_start(ap, xml);
    r = switch_xml_vget(xml, ap);
    va_end(ap);
    return r;
}

// returns a null terminated array of processing instructions for the given
// target
SWITCH_DECLARE(const char **) switch_xml_pi(switch_xml_t xml, const char *target)
{
    switch_xml_root_t root = (switch_xml_root_t)xml;
    int i = 0;

    if (! root) return (const char **)SWITCH_XML_NIL;
    while (root->xml.parent) root = (switch_xml_root_t)root->xml.parent; // root tag
    while (root->pi[i] && strcmp(target, root->pi[i][0])) i++; // find target
    return (const char **)((root->pi[i]) ? root->pi[i] + 1 : SWITCH_XML_NIL);
}

// set an error string and return root
static switch_xml_t switch_xml_err(switch_xml_root_t root, char *s, const char *err, ...)
{
    va_list ap;
    int line = 1;
    char *t, fmt[SWITCH_XML_ERRL];
    
    for (t = root->s; t && t < s; t++) if (*t == '\n') line++;
    snprintf(fmt, SWITCH_XML_ERRL, "[error near line %d]: %s", line, err);

    va_start(ap, err);
    vsnprintf(root->err, SWITCH_XML_ERRL, fmt, ap);
    va_end(ap);

    return &root->xml;
}

// Recursively decodes entity and character references and normalizes new lines
// ent is a null terminated array of alternating entity names and values. set t
// to '&' for general entity decoding, '%' for parameter entity decoding, 'c'
// for cdata sections, ' ' for attribute normalization, or '*' for non-cdata
// attribute normalization. Returns s, or if the decoded string is longer than
// s, returns a malloced string that must be freed.
static char *switch_xml_decode(char *s, char **ent, char t)
{
    char *e, *r = s, *m = s;
    long b, c, d, l;

    for (; *s; s++) { // normalize line endings
        while (*s == '\r') {
            *(s++) = '\n';
            if (*s == '\n') memmove(s, (s + 1), strlen(s));
        }
    }
    
    for (s = r; ; ) {
        while (*s && *s != '&' && (*s != '%' || t != '%') && !isspace((int)(*s))) s++;

        if (! *s) break;
        else if (t != 'c' && ! strncmp(s, "&#", 2)) { // character reference
            if (s[2] == 'x') c = strtol(s + 3, &e, 16); // base 16
            else c = strtol(s + 2, &e, 10); // base 10
            if (! c || *e != ';') { s++; continue; } // not a character ref

            if (c < 0x80) *(s++) = (char)c; // US-ASCII subset
            else { // multi-byte UTF-8 sequence
                for (b = 0, d = c; d; d /= 2) b++; // number of bits in c
                b = (b - 2) / 5; // number of bytes in payload
                *(s++) = (char)((0xFF << (7 - b)) | (c >> (6 * b))); // head
                while (b) *(s++) = (char)(0x80 | ((c >> (6 * --b)) & 0x3F)); // payload
            }

            memmove(s, strchr(s, ';') + 1, strlen(strchr(s, ';')));
        }
        else if ((*s == '&' && (t == '&' || t == ' ' || t == '*')) ||
                 (*s == '%' && t == '%')) { // entity reference
            for (b = 0; ent[b] && strncmp(s + 1, ent[b], strlen(ent[b]));
                 b += 2); // find entity in entity list

            if (ent[b++]) { // found a match
                if ((c = (long)strlen(ent[b])) - 1 > (e = strchr(s, ';')) - s) {
                    l = (d = (long)(s - r)) + c + (long)strlen(e); // new length
                    r = (r == m) ? strcpy(malloc(l), r) : realloc(r, l);
                    e = strchr((s = r + d), ';'); // fix up pointers
                }

                memmove(s + c, e + 1, strlen(e)); // shift rest of string
                strncpy(s, ent[b], c); // copy in replacement text
            }
            else s++; // not a known entity
        }
        else if ((t == ' ' || t == '*') && isspace((int)(*s))) *(s++) = ' ';
        else s++; // no decoding needed
    }

    if (t == '*') { // normalize spaces for non-cdata attributes
        for (s = r; *s; s++) {
            if ((l = (long)strspn(s, " "))) memmove(s, s + l, strlen(s + l) + 1);
            while (*s && *s != ' ') s++;
        }
        if (--s >= r && *s == ' ') *s = '\0'; // trim any trailing space
    }
    return r;
}

// called when parser finds start of new tag
static void switch_xml_open_tag(switch_xml_root_t root, char *name, char **attr)
{
    switch_xml_t xml = root->cur;
    
    if (xml->name) xml = switch_xml_add_child(xml, name, strlen(xml->txt));
    else xml->name = name; // first open tag

    xml->attr = attr;
    root->cur = xml; // update tag insertion point
}

// called when parser finds character content between open and closing tag
static void switch_xml_char_content(switch_xml_root_t root, char *s, switch_size_t len, char t)
{
    switch_xml_t xml = root->cur;
    char *m = s;
    switch_size_t l;

    if (! xml || ! xml->name || ! len) return; // sanity check

    s[len] = '\0'; // null terminate text (calling functions anticipate this)
    len = strlen(s = switch_xml_decode(s, root->ent, t)) + 1;

    if (! *(xml->txt)) xml->txt = s; // initial character content
    else { // allocate our own memory and make a copy
        xml->txt = (xml->flags & SWITCH_XML_TXTM) // allocate some space
                   ? realloc(xml->txt, (l = strlen(xml->txt)) + len)
                   : strcpy(malloc((l = strlen(xml->txt)) + len), xml->txt);
        strcpy(xml->txt + l, s); // add new char content
        if (s != m) free(s); // free s if it was malloced by switch_xml_decode()
    }

    if (xml->txt != m) switch_xml_set_flag(xml, SWITCH_XML_TXTM);
}

// called when parser finds closing tag
static switch_xml_t switch_xml_close_tag(switch_xml_root_t root, char *name, char *s)
{
    if (! root->cur || ! root->cur->name || strcmp(name, root->cur->name))
        return switch_xml_err(root, s, "unexpected closing tag </%s>", name);

    root->cur = root->cur->parent;
    return NULL;
}

// checks for circular entity references, returns non-zero if no circular
// references are found, zero otherwise
static int switch_xml_ent_ok(char *name, char *s, char **ent)
{
    int i;

    for (; ; s++) {
        while (*s && *s != '&') s++; // find next entity reference
        if (! *s) return 1;
        if (! strncmp(s + 1, name, strlen(name))) return 0; // circular ref.
        for (i = 0; ent[i] && strncmp(ent[i], s + 1, strlen(ent[i])); i += 2);
        if (ent[i] && ! switch_xml_ent_ok(name, ent[i + 1], ent)) return 0;
    }
}

// called when the parser finds a processing instruction
static void switch_xml_proc_inst(switch_xml_root_t root, char *s, switch_size_t len)
{
    int i = 0, j = 1;
    char *target = s;

    s[len] = '\0'; // null terminate instruction
    if (*(s += strcspn(s, SWITCH_XML_WS))) {
        *s = '\0'; // null terminate target
        s += strspn(s + 1, SWITCH_XML_WS) + 1; // skip whitespace after target
    }

    if (! strcmp(target, "xml")) { // <?xml ... ?>
        if ((s = strstr(s, "standalone")) && ! strncmp(s + strspn(s + 10,
            SWITCH_XML_WS "='\"") + 10, "yes", 3)) root->standalone = 1;
        return;
    }

    if (! root->pi[0]) *(root->pi = malloc(sizeof(char **))) = NULL; //first pi

    while (root->pi[i] && strcmp(target, root->pi[i][0])) i++; // find target
    if (! root->pi[i]) { // new target
        root->pi = realloc(root->pi, sizeof(char **) * (i + 2));
        root->pi[i] = malloc(sizeof(char *) * 3);
        root->pi[i][0] = target;
        root->pi[i][1] = (char *)(root->pi[i + 1] = NULL); // terminate pi list
        root->pi[i][2] = strdup(""); // empty document position list
    }

    while (root->pi[i][j]) j++; // find end of instruction list for this target
    root->pi[i] = realloc(root->pi[i], sizeof(char *) * (j + 3));
    root->pi[i][j + 2] = realloc(root->pi[i][j + 1], j + 1);
    strcpy(root->pi[i][j + 2] + j - 1, (root->xml.name) ? ">" : "<");
    root->pi[i][j + 1] = NULL; // null terminate pi list for this target
    root->pi[i][j] = s; // set instruction
}

// called when the parser finds an internal doctype subset
static short switch_xml_internal_dtd(switch_xml_root_t root, char *s, switch_size_t len)
{
    char q, *c, *t, *n = NULL, *v, **ent, **pe;
    int i, j;
    
    pe = memcpy(malloc(sizeof(SWITCH_XML_NIL)), SWITCH_XML_NIL, sizeof(SWITCH_XML_NIL));

    for (s[len] = '\0'; s; ) {
        while (*s && *s != '<' && *s != '%') s++; // find next declaration

        if (! *s) break;
        else if (! strncmp(s, "<!ENTITY", 8)) { // parse entity definitions
            c = s += strspn(s + 8, SWITCH_XML_WS) + 8; // skip white space separator
            n = s + strspn(s, SWITCH_XML_WS "%"); // find name
            *(s = n + strcspn(n, SWITCH_XML_WS)) = ';'; // append ; to name

            v = s + strspn(s + 1, SWITCH_XML_WS) + 1; // find value
            if ((q = *(v++)) != '"' && q != '\'') { // skip externals
                s = strchr(s, '>');
                continue;
            }

            for (i = 0, ent = (*c == '%') ? pe : root->ent; ent[i]; i++);
            ent = realloc(ent, (i + 3) * sizeof(char *)); // space for next ent
            if (*c == '%') pe = ent;
            else root->ent = ent;

            *(++s) = '\0'; // null terminate name
            if ((s = strchr(v, q))) *(s++) = '\0'; // null terminate value
            ent[i + 1] = switch_xml_decode(v, pe, '%'); // set value
            ent[i + 2] = NULL; // null terminate entity list
            if (! switch_xml_ent_ok(n, ent[i + 1], ent)) { // circular reference
                if (ent[i + 1] != v) free(ent[i + 1]);
                switch_xml_err(root, v, "circular entity declaration &%s", n);
                break;
            }
            else ent[i] = n; // set entity name
        }
        else if (! strncmp(s, "<!ATTLIST", 9)) { // parse default attributes
            t = s + strspn(s + 9, SWITCH_XML_WS) + 9; // skip whitespace separator
            if (! *t) { switch_xml_err(root, t, "unclosed <!ATTLIST"); break; }
            if (*(s = t + strcspn(t, SWITCH_XML_WS ">")) == '>') continue;
            else *s = '\0'; // null terminate tag name
            for (i = 0; root->attr[i] && strcmp(n, root->attr[i][0]); i++);

            while (*(n = ++s + strspn(s, SWITCH_XML_WS)) && *n != '>') {
                if (*(s = n + strcspn(n, SWITCH_XML_WS))) *s = '\0'; // attr name
                else { switch_xml_err(root, t, "malformed <!ATTLIST"); break; }

                s += strspn(s + 1, SWITCH_XML_WS) + 1; // find next token
                c = (strncmp(s, "CDATA", 5)) ? "*" : " "; // is it cdata?
                if (! strncmp(s, "NOTATION", 8))
                    s += strspn(s + 8, SWITCH_XML_WS) + 8;
                s = (*s == '(') ? strchr(s, ')') : s + strcspn(s, SWITCH_XML_WS);
                if (! s) { switch_xml_err(root, t, "malformed <!ATTLIST"); break; }

                s += strspn(s, SWITCH_XML_WS ")"); // skip white space separator
                if (! strncmp(s, "#FIXED", 6))
                    s += strspn(s + 6, SWITCH_XML_WS) + 6;
                if (*s == '#') { // no default value
                    s += strcspn(s, SWITCH_XML_WS ">") - 1;
                    if (*c == ' ') continue; // cdata is default, nothing to do
                    v = NULL;
                }
                else if ((*s == '"' || *s == '\'')  &&  // default value
                         (s = strchr(v = s + 1, *s))) *s = '\0';
                else { switch_xml_err(root, t, "malformed <!ATTLIST"); break; }

                if (! root->attr[i]) { // new tag name
                    root->attr = (! i) ? malloc(2 * sizeof(char **))
                                       : realloc(root->attr,
                                                 (i + 2) * sizeof(char **));
                    root->attr[i] = malloc(2 * sizeof(char *));
                    root->attr[i][0] = t; // set tag name
                    root->attr[i][1] = (char *)(root->attr[i + 1] = NULL);
                }

                for (j = 1; root->attr[i][j]; j += 3); // find end of list
                root->attr[i] = realloc(root->attr[i],
                                        (j + 4) * sizeof(char *));

                root->attr[i][j + 3] = NULL; // null terminate list
                root->attr[i][j + 2] = c; // is it cdata?
                root->attr[i][j + 1] = (v) ? switch_xml_decode(v, root->ent, *c)
                                           : NULL;
                root->attr[i][j] = n; // attribute name 
            }
        }
        else if (! strncmp(s, "<!--", 4)) s = strstr(s + 4, "-->"); // comments
        else if (! strncmp(s, "<?", 2)) { // processing instructions
            if ((s = strstr(c = s + 2, "?>")))
                switch_xml_proc_inst(root, c, s++ - c);
        }
        else if (*s == '<') s = strchr(s, '>'); // skip other declarations
        else if (*(s++) == '%' && ! root->standalone) break;
    }

    free(pe);
    return ! *root->err;
}

// Converts a UTF-16 string to UTF-8. Returns a new string that must be freed
// or NULL if no conversion was needed.
static char *switch_xml_str2utf8(char **s, switch_size_t *len)
{
    char *u;
    switch_size_t l = 0, sl, max = *len;
    long c, d;
    int b, be = (**s == '\xFE') ? 1 : (**s == '\xFF') ? 0 : -1;

    if (be == -1) return NULL; // not UTF-16

    u = malloc(max);
    for (sl = 2; sl < *len - 1; sl += 2) {
        c = (be) ? (((*s)[sl] & 0xFF) << 8) | ((*s)[sl + 1] & 0xFF)  //UTF-16BE
                 : (((*s)[sl + 1] & 0xFF) << 8) | ((*s)[sl] & 0xFF); //UTF-16LE
        if (c >= 0xD800 && c <= 0xDFFF && (sl += 2) < *len - 1) { // high-half
            d = (be) ? (((*s)[sl] & 0xFF) << 8) | ((*s)[sl + 1] & 0xFF)
                     : (((*s)[sl + 1] & 0xFF) << 8) | ((*s)[sl] & 0xFF);
            c = (((c & 0x3FF) << 10) | (d & 0x3FF)) + 0x10000;
        }

        while (l + 6 > max) u = realloc(u, max += SWITCH_XML_BUFSIZE);
        if (c < 0x80) u[l++] = (char)c; // US-ASCII subset
        else { // multi-byte UTF-8 sequence
            for (b = 0, d = c; d; d /= 2) b++; // bits in c
            b = (b - 2) / 5; // bytes in payload
            u[l++] = (char)((0xFF << (7 - b)) | (c >> (6 * b))); // head
            while (b) u[l++] = (char)(0x80 | ((c >> (6 * --b)) & 0x3F)); // payload
        }
    }
    return *s = realloc(u, *len = l);
}

// frees a tag attribute list
static void switch_xml_free_attr(char **attr) {
    int i = 0;
    char *m;
    
    if (! attr || attr == SWITCH_XML_NIL) return; // nothing to free
    while (attr[i]) i += 2; // find end of attribute list
    m = attr[i + 1]; // list of which names and values are malloced
    for (i = 0; m[i]; i++) {
        if (m[i] & SWITCH_XML_NAMEM) free(attr[i * 2]);
        if (m[i] & SWITCH_XML_TXTM) free(attr[(i * 2) + 1]);
    }
    free(m);
    free(attr);
}

// parse the given xml string and return an switch_xml structure
SWITCH_DECLARE(switch_xml_t) switch_xml_parse_str(char *s, switch_size_t len)
{
    switch_xml_root_t root = (switch_xml_root_t)switch_xml_new(NULL);
    char q, e, *d, **attr, **a = NULL; // initialize a to avoid compile warning
    int l, i, j;

    root->m = s;
    if (! len) return switch_xml_err(root, s, "root tag missing");
    root->u = switch_xml_str2utf8(&s, &len); // convert utf-16 to utf-8
    root->e = (root->s = s) + len; // record start and end of work area
    
    e = s[len - 1]; // save end char
    s[len - 1] = '\0'; // turn end char into null terminator

    while (*s && *s != '<') s++; // find first tag
    if (! *s) return switch_xml_err(root, s, "root tag missing");

    for (; ; ) {
        attr = (char **)SWITCH_XML_NIL;
        d = ++s;
        
        if (isalpha((int)(*s)) || *s == '_' || *s == ':' || (int8_t) *s < '\0') { // new tag
            if (! root->cur)
                return switch_xml_err(root, d, "markup outside of root element");

            s += strcspn(s, SWITCH_XML_WS "/>");
            while (isspace((int)(*s))) *(s++) = '\0'; // null terminate tag name
  
            if (*s && *s != '/' && *s != '>') // find tag in default attr list
                for (i = 0; (a = root->attr[i]) && strcmp(a[0], d); i++);

            for (l = 0; *s && *s != '/' && *s != '>'; l += 2) { // new attrib
                attr = (l) ? realloc(attr, (l + 4) * sizeof(char *))
                           : malloc(4 * sizeof(char *)); // allocate space
                attr[l + 3] = (l) ? realloc(attr[l + 1], (l / 2) + 2)
                                  : malloc(2); // mem for list of maloced vals
                strcpy(attr[l + 3] + (l / 2), " "); // value is not malloced
                attr[l + 2] = NULL; // null terminate list
                attr[l + 1] = ""; // temporary attribute value
                attr[l] = s; // set attribute name

                s += strcspn(s, SWITCH_XML_WS "=/>");
                if (*s == '=' || isspace((int)(*s))) { 
                    *(s++) = '\0'; // null terminate tag attribute name
                    q = *(s += strspn(s, SWITCH_XML_WS "="));
                    if (q == '"' || q == '\'') { // attribute value
                        attr[l + 1] = ++s;
                        while (*s && *s != q) s++;
                        if (*s) *(s++) = '\0'; // null terminate attribute val
                        else {
                            switch_xml_free_attr(attr);
                            return switch_xml_err(root, d, "missing %c", q);
                        }

                        for (j = 1; a && a[j] && strcmp(a[j], attr[l]); j +=3);
                        attr[l + 1] = switch_xml_decode(attr[l + 1], root->ent, (a
                                                   && a[j]) ? *a[j + 2] : ' ');
                        if (attr[l + 1] < d || attr[l + 1] > s)
                            attr[l + 3][l / 2] = SWITCH_XML_TXTM; // value malloced
                    }
                }
                while (isspace((int)(*s))) s++;
            }

            if (*s == '/') { // self closing tag
                *(s++) = '\0';
                if ((*s && *s != '>') || (! *s && e != '>')) {
                    if (l) switch_xml_free_attr(attr);
                    return switch_xml_err(root, d, "missing >");
                }
                switch_xml_open_tag(root, d, attr);
                switch_xml_close_tag(root, d, s);
            }
            else if ((q = *s) == '>' || (! *s && e == '>')) { // open tag
                *s = '\0'; // temporarily null terminate tag name
                switch_xml_open_tag(root, d, attr);
                *s = q;
            }
            else {
                if (l) switch_xml_free_attr(attr);
                return switch_xml_err(root, d, "missing >"); 
            }
        }
        else if (*s == '/') { // close tag
            s += strcspn(d = s + 1, SWITCH_XML_WS ">") + 1;
            if (! (q = *s) && e != '>') return switch_xml_err(root, d, "missing >");
            *s = '\0'; // temporarily null terminate tag name
            if (switch_xml_close_tag(root, d, s)) return &root->xml;
            if (isspace((int)(*s = q))) s += strspn(s, SWITCH_XML_WS);
        }
        else if (! strncmp(s, "!--", 3)) { // comment
            if (! (s = strstr(s + 3, "--")) || (*(s += 2) != '>' && *s) ||
                (! *s && e != '>')) return switch_xml_err(root, d, "unclosed <!--");
        }
        else if (! strncmp(s, "![CDATA[", 8)) { // cdata
            if ((s = strstr(s, "]]>")))
                switch_xml_char_content(root, d + 8, (s += 2) - d - 10, 'c');
            else return switch_xml_err(root, d, "unclosed <![CDATA[");
        }
        else if (! strncmp(s, "!DOCTYPE", 8)) { // dtd
            for (l = 0; *s && ((! l && *s != '>') || (l && (*s != ']' || 
                 *(s + strspn(s + 1, SWITCH_XML_WS) + 1) != '>')));
                 l = (*s == '[') ? 1 : l) s += strcspn(s + 1, "[]>") + 1;
            if (! *s && e != '>')
                return switch_xml_err(root, d, "unclosed <!DOCTYPE");
            d = (l) ? strchr(d, '[') + 1 : d;
            if (l && ! switch_xml_internal_dtd(root, d, s++ - d)) return &root->xml;
        }
        else if (*s == '?') { // <?...?> processing instructions
            do { s = strchr(s, '?'); } while (s && *(++s) && *s != '>');
            if (! s || (! *s && e != '>')) 
                return switch_xml_err(root, d, "unclosed <?");
            else switch_xml_proc_inst(root, d + 1, s - d - 2);
        }
        else return switch_xml_err(root, d, "unexpected <");
        
        if (! s || ! *s) break;
        *s = '\0';
        d = ++s;
        if (*s && *s != '<') { // tag character content
            while (*s && *s != '<') s++;
            if (*s) switch_xml_char_content(root, d, s - d, '&');
            else break;
        }
        else if (! *s) break;
    }

    if (! root->cur) return &root->xml;
    else if (! root->cur->name) return switch_xml_err(root, d, "root tag missing");
    else return switch_xml_err(root, d, "unclosed tag <%s>", root->cur->name);
}

// Wrapper for switch_xml_parse_str() that accepts a file stream. Reads the entire
// stream into memory and then parses it. For xml files, use switch_xml_parse_file()
// or switch_xml_parse_fd()
SWITCH_DECLARE(switch_xml_t) switch_xml_parse_fp(FILE *fp)
{
    switch_xml_root_t root;
    switch_size_t l, len = 0;
    char *s;

    if (! (s = malloc(SWITCH_XML_BUFSIZE))) return NULL;
    do {
        len += (l = fread((s + len), 1, SWITCH_XML_BUFSIZE, fp));
        if (l == SWITCH_XML_BUFSIZE) s = realloc(s, len + SWITCH_XML_BUFSIZE);
    } while (s && l == SWITCH_XML_BUFSIZE);

    if (! s) return NULL;
    root = (switch_xml_root_t)switch_xml_parse_str(s, len);
    root->dynamic = 1; // so we know to free s in switch_xml_free()
    return &root->xml;
}

// A wrapper for switch_xml_parse_str() that accepts a file descriptor. First
// attempts to mem map the file. Failing that, reads the file into memory.
// Returns NULL on failure.
SWITCH_DECLARE(switch_xml_t) switch_xml_parse_fd(int fd)
{
    switch_xml_root_t root;
    struct stat st;
    switch_size_t l;
    void *m;

    if (fd < 0) return NULL;
    fstat(fd, &st);

#ifdef HAVE_MMAP
    l = (st.st_size + sysconf(_SC_PAGESIZE) - 1) & ~(sysconf(_SC_PAGESIZE) -1);
    if ((m = mmap(NULL, l, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0)) !=
        MAP_FAILED) {
        madvise(m, l, MADV_SEQUENTIAL); // optimize for sequential access
        root = (switch_xml_root_t)switch_xml_parse_str(m, st.st_size);
        madvise(m, root->len = l, MADV_NORMAL); // put it back to normal
    }
    else { // mmap failed, read file into memory
#endif // HAVE_MMAP
        l = read(fd, m = malloc(st.st_size), st.st_size);
        root = (switch_xml_root_t)switch_xml_parse_str(m, l);
        root->dynamic = 1; // so we know to free s in switch_xml_free()
#ifdef HAVE_MMAP
    }
#endif // HAVE_MMAP
    return &root->xml;
}

// a wrapper for switch_xml_parse_fd that accepts a file name
SWITCH_DECLARE(switch_xml_t) switch_xml_parse_file(const char *file)
{
    int fd = open(file, O_RDONLY, 0);
    switch_xml_t xml = switch_xml_parse_fd(fd);
    
    if (fd >= 0) close(fd);
    return xml;
}


SWITCH_DECLARE(switch_status_t) switch_xml_locate(char *section,
												  char *tag_name,
												  char *key_name,
												  char *key_value,
												  switch_xml_t *root,
												  switch_xml_t *node,
												  char *params)
{
	switch_xml_t conf = NULL;
	switch_xml_t tag = NULL;
	switch_xml_t xml = NULL;
	switch_xml_binding_t *binding;
	uint8_t loops = 0;

	switch_mutex_lock(XML_LOCK);

	for(binding = BINDINGS; binding; binding = binding->next) {
		switch_xml_section_t sections = switch_xml_parse_section_string(section);

		if (binding->sections && !(sections & binding->sections)) {
			continue;
		}

		if ((xml = binding->function(section, tag_name, key_name, key_value, params))) {
			const char *err = NULL;
			
			err = switch_xml_error(xml);
			if (switch_strlen_zero(err)) {
				if ((conf = switch_xml_find_child(xml, "section", "name", "result"))) {
					switch_xml_t p;
					const char *aname;

					if ((p = switch_xml_child(conf, "result"))) {
						aname = switch_xml_attr(p, "status");
						if (aname && !strcasecmp(aname, "not found")) {
							switch_xml_free(xml);
							xml = NULL;
							continue;
						}
					}
				}
				break;
			} else {
				switch_log_printf(SWITCH_CHANNEL_LOG, SWITCH_LOG_ERROR, "Error[%s]\n", err);
				switch_xml_free(xml);
				xml = NULL;
			}
		}
	}
	switch_mutex_unlock(XML_LOCK);

	for(;;) {
		if (!xml) {
			if (!(xml = switch_xml_root())) {
				*node = NULL;
				*root = NULL;
				return SWITCH_STATUS_FALSE;
			}
		}

		if ((conf = switch_xml_find_child(xml, "section", "name", section)) && 
			(tag = switch_xml_find_child(conf, tag_name, key_name, key_value))) {
			*node = tag;
			*root = xml;
			return SWITCH_STATUS_SUCCESS;
		} else {
			switch_xml_free(xml);
			xml = NULL;
			*node = NULL;
			*root = NULL;
			if (loops++ > 1) {
				break;
			}
		}
	}

	return SWITCH_STATUS_FALSE;
}


SWITCH_DECLARE(switch_xml_t) switch_xml_root(void)
{
	lock_count++;
	switch_thread_rwlock_rdlock(RWLOCK);
	return MAIN_XML_ROOT;
}

SWITCH_DECLARE(switch_xml_t) switch_xml_open_root(uint8_t reload, const char **err)
{
	char path_buf[1024];
	uint8_t hasmain = 0;
	
	switch_mutex_lock(XML_LOCK);

	if (MAIN_XML_ROOT) {
		switch_xml_t xml;
		hasmain++;

		if (!reload) {
			switch_mutex_unlock(XML_LOCK);
			return switch_xml_root();
		}
		xml = MAIN_XML_ROOT;
		MAIN_XML_ROOT = NULL;
		switch_thread_rwlock_wrlock(RWLOCK);
		switch_xml_free(xml);
	}

	snprintf(path_buf, sizeof(path_buf), "%s%s%s", SWITCH_GLOBAL_dirs.conf_dir, SWITCH_PATH_SEPARATOR, "freeswitch.xml");
	if ((MAIN_XML_ROOT = switch_xml_parse_file(path_buf))) {
		*err = switch_xml_error(MAIN_XML_ROOT);

		if (!switch_strlen_zero(*err)) {
			switch_xml_free(MAIN_XML_ROOT);
			MAIN_XML_ROOT = NULL;
		} else {
			*err = "Success";
			switch_set_flag(MAIN_XML_ROOT, SWITCH_XML_ROOT);
		}
	} else {
		*err = "Cannot Open XML Root!";
	}

	if (hasmain) {
		switch_thread_rwlock_unlock(RWLOCK);
	}
	switch_mutex_unlock(XML_LOCK);

	return switch_xml_root();
}


SWITCH_DECLARE(switch_status_t) switch_xml_init(switch_memory_pool_t *pool, const char **err)
{
	switch_xml_t xml;
	XML_MEMORY_POOL = pool;
	*err = "Success";

	switch_mutex_init(&XML_LOCK, SWITCH_MUTEX_NESTED, XML_MEMORY_POOL);
	switch_thread_rwlock_create(&RWLOCK, XML_MEMORY_POOL);

	assert(pool != NULL);

	if((xml=switch_xml_open_root(FALSE, err))) {
		switch_xml_free(xml);
		return SWITCH_STATUS_SUCCESS;
	} else {
		return SWITCH_STATUS_FALSE;
	}
}

SWITCH_DECLARE(switch_status_t) switch_xml_destroy(void)
{
	if (MAIN_XML_ROOT) {
		switch_xml_t xml = MAIN_XML_ROOT;
		MAIN_XML_ROOT = NULL;
		switch_xml_free(xml);
		return SWITCH_STATUS_SUCCESS;
	}

	return SWITCH_STATUS_FALSE;
}

SWITCH_DECLARE(switch_xml_t) switch_xml_open_cfg(char *file_path, switch_xml_t *node, char *params)
{
	switch_xml_t xml = NULL, cfg = NULL;

	*node = NULL;

	assert(MAIN_XML_ROOT != NULL);

	if (switch_xml_locate("configuration", "configuration", "name", file_path, &xml, &cfg, params) == SWITCH_STATUS_SUCCESS) {
		*node = cfg;
	}

	return xml;	
	
}


// Encodes ampersand sequences appending the results to *dst, reallocating *dst
// if length excedes max. a is non-zero for attribute encoding. Returns *dst
static char *switch_xml_ampencode(const char *s, switch_size_t len, char **dst, switch_size_t *dlen, switch_size_t *max, short a)
{
    const char *e = NULL;

	if (len) {
		e = s + len;
	}
    
    while (s != e) {
        while (*dlen + 10 > *max) *dst = realloc(*dst, *max += SWITCH_XML_BUFSIZE);

        switch (*s) {
        case '\0': return *dst;
        case '&': *dlen += sprintf(*dst + *dlen, "&amp;"); break;
        case '<': *dlen += sprintf(*dst + *dlen, "&lt;"); break;
        case '>': *dlen += sprintf(*dst + *dlen, "&gt;"); break;
        case '"': *dlen += sprintf(*dst + *dlen, (a) ? "&quot;" : "\""); break;
        case '\n': *dlen += sprintf(*dst + *dlen, (a) ? "&#xA;" : "\n"); break;
        case '\t': *dlen += sprintf(*dst + *dlen, (a) ? "&#x9;" : "\t"); break;
        case '\r': *dlen += sprintf(*dst + *dlen, "&#xD;"); break;
        default: (*dst)[(*dlen)++] = *s;
        }
		s++;
    }
    return *dst;
}

#define XML_INDENT "  "
// Recursively converts each tag to xml appending it to *s. Reallocates *s if
// its length excedes max. start is the location of the previous tag in the
// parent tag's character content. Returns *s.
static char *switch_xml_toxml_r(switch_xml_t xml, char **s, switch_size_t *len, switch_size_t *max,
                    switch_size_t start, char ***attr, uint32_t *count)
{
    int i, j;
    char *txt = (xml->parent) ? xml->parent->txt : "";
    switch_size_t off = 0;
	uint32_t lcount = 0;
	
    // parent character content up to this tag
    *s = switch_xml_ampencode(txt + start, xml->off - start, s, len, max, 0);

    while (*len + strlen(xml->name) + 5 + (strlen(XML_INDENT) * (*count)) > *max) // reallocate s
        *s = realloc(*s, *max += SWITCH_XML_BUFSIZE);

	for (lcount = 0; lcount < *count; lcount++) {
		*len += sprintf(*s + *len, "%s", XML_INDENT); // indent
	}
	
    *len += sprintf(*s + *len, "<%s", xml->name); // open tag
    for (i = 0; xml->attr[i]; i += 2) { // tag attributes
        if (switch_xml_attr(xml, xml->attr[i]) != xml->attr[i + 1]) continue;
        while (*len + strlen(xml->attr[i]) + 7 + (strlen(XML_INDENT) * (*count)) > *max) // reallocate s
            *s = realloc(*s, *max += SWITCH_XML_BUFSIZE);

        *len += sprintf(*s + *len, " %s=\"", xml->attr[i]);
        switch_xml_ampencode(xml->attr[i + 1], 0, s, len, max, 1);
        *len += sprintf(*s + *len, "\"");
    }

    for (i = 0; attr[i] && strcmp(attr[i][0], xml->name); i++);
    for (j = 1; attr[i] && attr[i][j]; j += 3) { // default attributes
        if (! attr[i][j + 1] || switch_xml_attr(xml, attr[i][j]) != attr[i][j + 1])
            continue; // skip duplicates and non-values
        while (*len + strlen(attr[i][j]) + 8 + (strlen(XML_INDENT) * (*count)) > *max) // reallocate s
            *s = realloc(*s, *max += SWITCH_XML_BUFSIZE);

        *len += sprintf(*s + *len, " %s=\"", attr[i][j]);
        switch_xml_ampencode(attr[i][j + 1], 0, s, len, max, 1);
        *len += sprintf(*s + *len, "\"");
    }

    *len += sprintf(*s + *len, (xml->child || xml->txt) ? ">" : "/>\n");

	if (xml->child) {
		(*count)++;
		*s = switch_xml_toxml_r(xml->child, s, len, max, 0, attr, count);

	} else {
		*s = switch_xml_ampencode(xml->txt, 0, s, len, max, 0);  //data
	}
	
    while (*len + strlen(xml->name) + 5 + (strlen(XML_INDENT) * (*count)) > *max) // reallocate s
        *s = realloc(*s, *max += SWITCH_XML_BUFSIZE);


	if (xml->child || xml->txt) {
		//for (lcount = 0; lcount < *count; lcount++) {
		//*len += sprintf(*s + *len, "%s", XML_INDENT); // indent
		//}
		*len += sprintf(*s + (*len), "</%s>\n", xml->name); // close tag
	}

    while (txt[off] && off < xml->off) off++; // make sure off is within bounds

	if (xml->ordered) {
		return switch_xml_toxml_r(xml->ordered, s, len, max, off, attr, count);

	} else {
		if (*count > 0)
			(*count)--;
		return switch_xml_ampencode(txt + off, 0, s, len, max, 0);
	}
}

// converts an switch_xml structure back to xml, returning it as a string that must
// be freed
SWITCH_DECLARE(char *) switch_xml_toxml(switch_xml_t xml)
{
    switch_xml_t p = (xml) ? xml->parent : NULL, o = (xml) ? xml->ordered : NULL;
    switch_xml_root_t root = (switch_xml_root_t)xml;
    switch_size_t len = 0, max = SWITCH_XML_BUFSIZE;
    char *s = strcpy(malloc(max), ""), *t, *n;
    int i, j, k;
	uint32_t count = 0;

    if (! xml || ! xml->name) return realloc(s, len + 1);
    while (root->xml.parent) root = (switch_xml_root_t)root->xml.parent; // root tag

    for (i = 0; ! p && root->pi[i]; i++) { // pre-root processing instructions
        for (k = 2; root->pi[i][k - 1]; k++);
        for (j = 1; (n = root->pi[i][j]); j++) {
            if (root->pi[i][k][j - 1] == '>') continue; // not pre-root
            while (len + strlen(t = root->pi[i][0]) + strlen(n) + 7 > max)
                s = realloc(s, max += SWITCH_XML_BUFSIZE);
            len += sprintf(s + len, "<?%s%s%s?>", t, *n ? " " : "", n);
        }
    }

    xml->parent = xml->ordered = NULL;
    s = switch_xml_toxml_r(xml, &s, &len, &max, 0, root->attr, &count);
    xml->parent = p;
    xml->ordered = o;

    for (i = 0; ! p && root->pi[i]; i++) { // post-root processing instructions
        for (k = 2; root->pi[i][k - 1]; k++);
        for (j = 1; (n = root->pi[i][j]); j++) {
            if (root->pi[i][k][j - 1] == '<') continue; // not post-root
            while (len + strlen(t = root->pi[i][0]) + strlen(n) + 7 > max)
                s = realloc(s, max += SWITCH_XML_BUFSIZE);
            len += sprintf(s + len, "\n<?%s%s%s?>", t, *n ? " " : "", n);
        }
    }
    return realloc(s, len + 1);
}

// free the memory allocated for the switch_xml structure
SWITCH_DECLARE(void) switch_xml_free(switch_xml_t xml)
{
    switch_xml_root_t root = (switch_xml_root_t)xml;
    int i, j;
    char **a, *s;


    if (! xml ) return;

	if (switch_test_flag(xml, SWITCH_XML_ROOT)) {
		if (lock_count > 0) {
			switch_thread_rwlock_unlock(RWLOCK);
			lock_count--;
		}
	}

	if (xml == MAIN_XML_ROOT) {
		return;
	} 

    switch_xml_free(xml->child);
    switch_xml_free(xml->ordered);

    if (! xml->parent) { // free root tag allocations
        for (i = 10; root->ent[i]; i += 2) // 0 - 9 are default entites (<>&"')
            if ((s = root->ent[i + 1]) < root->s || s > root->e) free(s);
        free(root->ent); // free list of general entities

        for (i = 0; (a = root->attr[i]); i++) {
            for (j = 1; a[j++]; j += 2) // free malloced attribute values
                if (a[j] && (a[j] < root->s || a[j] > root->e)) free(a[j]);
            free(a);
        }
        if (root->attr[0]) free(root->attr); // free default attribute list

        for (i = 0; root->pi[i]; i++) {
            for (j = 1; root->pi[i][j]; j++);
            free(root->pi[i][j + 1]);
            free(root->pi[i]);
        }            
        if (root->pi[0]) free(root->pi); // free processing instructions

        if (root->dynamic == 1) free(root->m); // malloced xml data
#ifdef HAVE_MMAP
        else if (root->len) munmap(root->m, root->len); // mem mapped xml data
#endif // HAVE_MMAP
        if (root->u) free(root->u); // utf8 conversion
    }

    switch_xml_free_attr(xml->attr); // tag attributes
    if ((xml->flags & SWITCH_XML_TXTM)) free(xml->txt); // character content
    if ((xml->flags & SWITCH_XML_NAMEM)) free(xml->name); // tag name
    free(xml);
}

// return parser error message or empty string if none
SWITCH_DECLARE(const char *) switch_xml_error(switch_xml_t xml)
{
    while (xml && xml->parent) xml = xml->parent; // find root tag
    return (xml) ? ((switch_xml_root_t)xml)->err : "";
}

// returns a new empty switch_xml structure with the given root tag name
SWITCH_DECLARE(switch_xml_t) switch_xml_new(const char *name)
{
    static char *ent[] = { "lt;", "&#60;", "gt;", "&#62;", "quot;", "&#34;",
                           "apos;", "&#39;", "amp;", "&#38;", NULL };
    switch_xml_root_t root = (switch_xml_root_t)memset(malloc(sizeof(struct switch_xml_root)), 
                                             '\0', sizeof(struct switch_xml_root));
    root->xml.name = (char *)name;
    root->cur = &root->xml;
    strcpy(root->err, root->xml.txt = "");
    root->ent = memcpy(malloc(sizeof(ent)), ent, sizeof(ent));
    root->attr = root->pi = (char ***)(root->xml.attr = SWITCH_XML_NIL);
    return &root->xml;
}

// Adds a child tag. off is the offset of the child tag relative to the start
// of the parent tag's character content. returns the child tag
switch_xml_t switch_xml_add_child(switch_xml_t xml, const char *name, switch_size_t off)
{
    switch_xml_t cur, head, child;

    if (! xml) return NULL;
    child = (switch_xml_t)memset(malloc(sizeof(struct switch_xml)), '\0',
                            sizeof(struct switch_xml));
    child->name = (char *)name;
    child->attr = SWITCH_XML_NIL;
    child->off = off;
    child->parent = xml;
    child->txt = "";

    if ((head = xml->child)) { // already have sub tags
        if (head->off <= off) { // not first subtag
            for (cur = head; cur->ordered && cur->ordered->off <= off;
                 cur = cur->ordered);
            child->ordered = cur->ordered;
            cur->ordered = child;
        }
        else { // first subtag
            child->ordered = head;
            xml->child = child;
        }

        for (cur = head; cur->sibling && strcmp(cur->name, name);
             cur = cur->sibling); // find tag type
        if (! strcmp(cur->name, name) && cur->off <= off) { //not first of type
            while (cur->next && cur->next->off <= off) cur = cur->next;
            child->next = cur->next;
            cur->next = child;
        }
        else { // first tag of this type
            if (cur->off > off) child->next = cur; // not only tag of this type
            for (cur = head; cur->sibling && cur->sibling->off <= off;
                 cur = cur->sibling);
            child->sibling = cur->sibling;
            cur->sibling = child;
        }
    }
    else xml->child = child; // only sub tag
    
    return child;
}

// sets the character content for the given tag and returns the tag
switch_xml_t switch_xml_set_txt(switch_xml_t xml, const char *txt)
{
    if (! xml) return NULL;
    if (xml->flags & SWITCH_XML_TXTM) free(xml->txt); // existing txt was malloced
    xml->flags &= ~SWITCH_XML_TXTM;
    xml->txt = (char *)txt;
    return xml;
}

// Sets the given tag attribute or adds a new attribute if not found. A value
// of NULL will remove the specified attribute.
SWITCH_DECLARE(void) switch_xml_set_attr(switch_xml_t xml, const char *name, const char *value)
{
    int l = 0, c;

    if (! xml) return;
    while (xml->attr[l] && strcmp(xml->attr[l], name)) l += 2;
    if (! xml->attr[l]) { // not found, add as new attribute
        if (! value) return; // nothing to do
        if (xml->attr == SWITCH_XML_NIL) { // first attribute
            xml->attr = malloc(4 * sizeof(char *));
            xml->attr[1] = strdup(""); // empty list of malloced names/vals
        }
        else xml->attr = realloc(xml->attr, (l + 4) * sizeof(char *));

        xml->attr[l] = (char *)name; // set attribute name
        xml->attr[l + 2] = NULL; // null terminate attribute list
        xml->attr[l + 3] = realloc(xml->attr[l + 1],
                                   (c = (int)strlen(xml->attr[l + 1])) + 2);
        strcpy(xml->attr[l + 3] + c, " "); // set name/value as not malloced
        if (xml->flags & SWITCH_XML_DUP) xml->attr[l + 3][c] = SWITCH_XML_NAMEM;
    }
    else if (xml->flags & SWITCH_XML_DUP) free((char *)name); // name was strduped

    for (c = l; xml->attr[c]; c += 2); // find end of attribute list
    if (xml->attr[c + 1][l / 2] & SWITCH_XML_TXTM) free(xml->attr[l + 1]); //old val
    if (xml->flags & SWITCH_XML_DUP) xml->attr[c + 1][l / 2] |= SWITCH_XML_TXTM;
    else xml->attr[c + 1][l / 2] &= ~SWITCH_XML_TXTM;

    if (value) xml->attr[l + 1] = (char *)value; // set attribute value
    else { // remove attribute
        if (xml->attr[c + 1][l / 2] & SWITCH_XML_NAMEM) free(xml->attr[l]);
        memmove(xml->attr + l, xml->attr + l + 2, (c - l + 2) * sizeof(char*));
        xml->attr = realloc(xml->attr, (c + 2) * sizeof(char *));
        memmove(xml->attr[c + 1] + (l / 2), xml->attr[c + 1] + (l / 2) + 1,
                (c / 2) - (l / 2)); // fix list of which name/vals are malloced
    }
    xml->flags &= ~SWITCH_XML_DUP; // clear strdup() flag
}

// sets a flag for the given tag and returns the tag
SWITCH_DECLARE(switch_xml_t) switch_xml_set_flag(switch_xml_t xml, switch_xml_flag_t flag)
{
    if (xml) xml->flags |= flag;
    return xml;
}

// removes a tag along with all its subtags
SWITCH_DECLARE(void) switch_xml_remove(switch_xml_t xml)
{
    switch_xml_t cur;

    if (! xml) return; // nothing to do
    if (xml->next) xml->next->sibling = xml->sibling; // patch sibling list

    if (xml->parent) { // not root tag
        cur = xml->parent->child; // find head of subtag list
        if (cur == xml) xml->parent->child = xml->ordered; // first subtag
        else { // not first subtag
            while (cur->ordered != xml) cur = cur->ordered;
            cur->ordered = cur->ordered->ordered; // patch ordered list

            cur = xml->parent->child; // go back to head of subtag list
            if (strcmp(cur->name, xml->name)) { // not in first sibling list
                while (strcmp(cur->sibling->name, xml->name))
                    cur = cur->sibling;
                if (cur->sibling == xml) { // first of a sibling list
                    cur->sibling = (xml->next) ? xml->next
                                               : cur->sibling->sibling;
                }
                else cur = cur->sibling; // not first of a sibling list
            }

            while (cur->next && cur->next != xml) cur = cur->next;
            if (cur->next) cur->next = cur->next->next; // patch next list
        }        
    }
    xml->ordered = NULL; // prevent switch_xml_free() from clobbering ordered list
    switch_xml_free(xml);
}

/* For Emacs:
 * Local Variables:
 * mode:c
 * indent-tabs-mode:nil
 * tab-width:4
 * c-basic-offset:4
 * End:
 * For VIM:
 * vim:set softtabstop=4 shiftwidth=4 tabstop=4 expandtab:
 */